Don't confuse true with correct. The sentence 'They get up...' is correct grammatically whether or not they really do get up early. It is only true if they actually do get up early

Because "he and she" form a plural subject (third person plural), you have to have a third person plural verb ending (without an "s" on the end of the verb: "get". This is just like many English verbs: "He writes" but "they write," "he runs" but "they run." If you were just writing about him, you would write "He gets up early every day. "

the phrasal verb is - get up In this sentence, it should read - they get up early every day. Hope this helps Jane :)